/Engine/Source/Runtime/CoreUObject/Public/UObject/UObjectGlobals.h
This and other AddPropertyReferences functions will hopefully merge into a single function in the future. They're kept separate initially to maintain exact semantics while replacing the much slower SerializeBin/TPropertyValueIterator/GetVerySlowReferenceCollectorArchive paths.
void AddReferencedObjects ( const [UScriptStruct](API\Runtime\CoreUObject\UObject\UScriptStruct) *& ScriptStruct, void * Instance, const [UObject](API\Runtime\CoreUObject\UObject\UObject) * ReferencingObject, const [FProperty](API\Runtime\CoreUObject\UObject\FProperty) * ReferencingProperty )